use std::ptr;
use std::ffi::{CString, CStr};
use std::str::from_utf8_unchecked;

use ffi::*;
use libc::c_int;
use ::Error;
use super::{Context, Filter};

pub struct Graph {
	ptr: *mut AVFilterGraph,
}

unsafe impl Send for Graph { }
unsafe impl Sync for Graph { }

impl Graph {
	pub unsafe fn wrap(ptr: *mut AVFilterGraph) -> Self {
		Graph { ptr: ptr }
	}

	pub unsafe fn as_ptr(&self) -> *const AVFilterGraph {
		self.ptr as *const _
	}

	pub unsafe fn as_mut_ptr(&mut self) -> *mut AVFilterGraph {
		self.ptr
	}
}

impl Graph {
	pub fn new() -> Self {
		unsafe {
			let ptr = avfilter_graph_alloc();

			if ptr.is_null() {
				panic!("out of memory");
			}

			Graph::wrap(ptr)
		}
	}

	pub fn validate(&mut self) -> Result<(), Error> {
		unsafe {
			match avfilter_graph_config(self.as_mut_ptr(), ptr::null_mut()) {
				0 => Ok(()),
				e => Err(Error::from(e))
			}
		}
	}

	pub fn add<'a, 'b>(&'a mut self, filter: &Filter, name: &str, args: &str) -> Result<Context<'b>, Error> where 'a: 'b {
		unsafe {
			let     name    = CString::new(name).unwrap();
			let     args    = CString::new(args).unwrap();
			let mut context = ptr::null_mut();

			match avfilter_graph_create_filter(&mut context as *mut *mut AVFilterContext,
				filter.as_ptr(),
				name.as_ptr(),
				args.as_ptr(),
				ptr::null_mut(),
				self.as_mut_ptr())
			{
				n if n >= 0 => Ok(Context::wrap(context)),
				e           => Err(Error::from(e)),
			}
		}
	}

	pub fn get<'a, 'b>(&'b mut self, name: &str) -> Option<Context<'b>> where 'a: 'b {
		unsafe {
			let name = CString::new(name).unwrap();
			let ptr  = avfilter_graph_get_filter(self.as_mut_ptr(), name.as_ptr());

			if ptr.is_null() {
				None
			}
			else {
				Some(Context::wrap(ptr))
			}
		}
	}

	pub fn dump(&self) -> String {
		unsafe {
			let ptr    = avfilter_graph_dump(self.as_ptr() as *mut _, ptr::null());
			let cstr   = from_utf8_unchecked(CStr::from_ptr((ptr)).to_bytes());
			let string = cstr.to_owned();

			av_free(ptr as *mut _);

			string
		}
	}

	pub fn input(&mut self, name: &str, pad: usize) -> Result<Parser, Error> {
		Parser::new(self).input(name, pad)
	}

	pub fn output(&mut self, name: &str, pad: usize) -> Result<Parser, Error> {
		Parser::new(self).output(name, pad)
	}

	pub fn parse(&mut self, spec: &str) -> Result<(), Error> {
		Parser::new(self).parse(spec)
	}
}

impl Drop for Graph {
	fn drop(&mut self) {
		unsafe {
			avfilter_graph_free(&mut self.as_mut_ptr());
		}
	}
}

pub struct Parser<'a> {
	graph:   &'a mut Graph,
	inputs:  *mut AVFilterInOut,
	outputs: *mut AVFilterInOut,
}

impl<'a> Parser<'a> {
	pub fn new(graph: &mut Graph) -> Parser {
		Parser {
			graph:   graph,
			inputs:  ptr::null_mut(),
			outputs: ptr::null_mut(),
		}
	}

	pub fn input(mut self, name: &str, pad: usize) -> Result<Self, Error> {
		unsafe {
			let mut context = try!(self.graph.get(name).ok_or(Error::InvalidData));
			let mut input   = avfilter_inout_alloc();

			if input.is_null() {
				panic!("out of memory");
			}

			let name = CString::new(name).unwrap();

			(*input).name       = av_strdup(name.as_ptr());
			(*input).filter_ctx = context.as_mut_ptr();
			(*input).pad_idx    = pad as c_int;
			(*input).next       = ptr::null_mut();

			if self.inputs.is_null() {
				self.inputs = input;
			}
			else {
				(*self.inputs).next = input;
			}
		}

		Ok(self)
	}

	pub fn output(mut self, name: &str, pad: usize) -> Result<Self, Error> {
		unsafe {
			let mut context = try!(self.graph.get(name).ok_or(Error::InvalidData));
			let mut output  = avfilter_inout_alloc();

			if output.is_null() {
				panic!("out of memory");
			}

			let name = CString::new(name).unwrap();

			(*output).name       = av_strdup(name.as_ptr());
			(*output).filter_ctx = context.as_mut_ptr();
			(*output).pad_idx    = pad as c_int;
			(*output).next       = ptr::null_mut();

			if self.outputs.is_null() {
				self.outputs = output;
			}
			else {
				(*self.outputs).next = output;
			}
		}

		Ok(self)
	}

	pub fn parse(mut self, spec: &str) -> Result<(), Error> {
		unsafe {
			let spec = CString::new(spec).unwrap();

			let result = avfilter_graph_parse_ptr(self.graph.as_mut_ptr(),
				spec.as_ptr(), &mut self.inputs, &mut self.outputs,
				ptr::null_mut());

			avfilter_inout_free(&mut self.inputs);
			avfilter_inout_free(&mut self.outputs);

			match result {
				n if n >= 0 => Ok(()),
				e           => Err(Error::from(e))
			}
		}
	}
}